Building Structure and a Method of Forming a Building Structure

ABSTRACT

A building structure comprising a footing ( 21   b ), wherein the footing ( 21   b ) includes a channel ( 23 ), and at least one panel ( 24 ), wherein the panel ( 24 ) is located within said channel ( 23 ), wherein the footing ( 21   b ) is disposed on a waterproofing membrane ( 22 ) which membrane extends along side walls of the footing ( 21   b ) and into said channel ( 23 ) and wherein the panel ( 24 ) has an external waterproofing membrane ( 25 ) that is in waterproof engagement with the membrane of the footing ( 21   b ) in the channel ( 23 ) and wherein the waterproofing membranes ( 22, 25 ) comprise an absorptive clay disposed between water permeable layers.

TECHNICAL FIELD

The present invention relates to a building structure and to a method offorming a building structure, in particular to a building structure andmethod that provides improved waterproofing properties in the buildingstructure.

BACKGROUND ART

Larger structures which are built on inground foundations arenotoriously difficult to waterproof and current procedures that are usedto provide waterproofing require peripheral excavation which are timeconsuming and costly and depending on site conditions, may restricteconomic use of a site.

In addition, excavations for inground foundations often are made at orbelow the water table which increases the need or an efficient means ofwaterproofing same.

We have now found a building structure and a method of forming abuilding structure which increases land use efficiencies and providesimproved waterproofing.

Further objects and advantages of the present invention will becomeapparent from the ensuing description which is given by way of example.

SUMMARY OF THE INVENTION

According to a first embodiment of the present invention, there isprovided a building structure comprising a footing, wherein the footingincludes a channel, and at least one panel, wherein the panel is locatedwithin said channel, wherein the footing is disposed on a waterproofingmembrane which membrane extends along side walls of the footing and intosaid channel and wherein the panel has an external waterproofingmembrane that is in waterproof engagement with the membrane of thefooting in the channel and wherein the waterproofing membranes comprisean absorptive clay disposed between water permeable layers.

In a second embodiment of the present invention there is provided amethod of constructing a building structure comprising:

(a) laying footing over a waterproofing membrane;

(b) creating a channel in the footing;

(c) extending the waterproofing membrane of the footing into thechannel;

(d) placing at least one panel in the channel wherein the panel has anexternal waterproofing membrane that is in waterproof engagement withthe membrane of the footing in the channel and wherein the waterproofingmembranes comprise an absorptive clay disposed between water permeablelayers.

DETAILED DESCRIPTION

The building structure of the present invention may be of any usefultype built on foundations as will be apparent to those skilled in theart. In particular, the building structure of the present invention isparticularly suited for inground foundations where the ground levelextends partway up the side walls of the building. The buildingstructure of the present invention is also useful in applications wherethe foundations are made at or below the water table and wherein thebuilding is exposed to penetration by groundwater.

The building structure may be of the type having peripheral footingsupon which the external walls are located and which support a suspendedtimber flooring above the ground. Another type of building structurethat may be constructed according to the present invention is a slabconstruction wherein an overground foundation in the form of a concreteslab is laid with an integral peripheral footing. Such slabconstructions are particularly advantageous when formed according to thepresent invention such that the waterproofing membrane can be disposedbelow the entirety of the overground foundation and extend upwards to aperipheral channel that extends around the foundation.

The footing for use in the present invention is preferably a pouredconcrete footing in which the channel is formed integrally with theformation of the footing by the use of formwork and the like.

In a building formed using an overground foundation integral with thefooting such as a slab construction, the channel is preferablysufficiently wide such that a spoon drain or the like may be provided onthe inner sides of the panels. The spoon drains may be formed by fillingthe channel after the panels and other elements have been insertedwithin the channel with a cement based material in which a spoon drainor the like is formed.

In building structures having discreet footings, it may be preferable toform the channel sufficiently wide such that the panel can be receivedwithin the channel and that the waterproofing membrane extending frombelow the footing can be also received in the channel with thewaterproofing membrane of the panel.

In the laying of the footing and overground foundation of a buildingstructure having a concrete slab formation the waterproofing membranemay be laid upon the ground upon which the overground foundation is tobe poured. The overground foundation may subsequently be poured and thewaterproofing membrane which extends beyond the footings may be extendedupwards along the side of the footings and into the channel. Thewaterproofing membrane may be cut such that the end of the membraneterminates at the base of the outer wall of the channel. The corners ofthe footings may be covered with waterproofing membrane by cutting thewaterproofing membrane such that the membrane may be extended upwardsover the sides of the footings in a manner that provides an overlap ofthe respective edges of waterproofing membrane. Preferably the overlapis of at least 100 mm. The overlap may be fixed to the adjacent membraneby any convenient means or may be held in place by the soil or otherearthen materials that surround the footing.

In building structures having discreet footings and which may support asuspended timber flooring, the waterproofing membrane may simply extendunder the footings and to the bases of the respective inner and outerwalls of the channel.

The panels may be of any convenient form. We have found that it isparticularly convenient to use precast concrete panels which may bepreformed and simply positioned in the channel in order to form thebuilding structure. Whilst precast concrete channels are preferred foruse in the present invention it will be apparent to those skilled in theart that the present invention envisages the use of other types ofpanels that may be either preformed or formed in situ.

The panels may be disposed directly on the base of the channel orpreferably on a grout such that the panels are elevated above the baseof the channel. Preferably strips of an absorptive clay are providedadjacent the base of the panel and, where a grout is used to maintainthe panels above the base of the channel, the absorptive strips may bepositioned along side the grout either underneath the panel or extendingtherefrom.

The panels have an external waterproofing membrane. The waterproofingmembrane may be applied to the external face of the panel, or, in thecase of a building structure having discreet foundations, the waterproofmembrane may be applied to both sides of the panel. The waterproofingmembrane may be formed integrally with the panel or applied to thepreformed panel. Where the panel is formed in situ, the waterproofingmembrane may be positioned within the channel and in waterproofingengagement with the waterproof membrane of the footing prior to theconstruction of the panel.

Where the panels are precast concrete panels, it is convenient that thewaterproofing membrane be formed integrally with the panel. The precastpanel may be formed with the waterproofing membrane already positionedon the outer face of the panel such that the panels may be simplylowered into the respective channels.

At the corner of the building structure, it is convenient to employprecast panels with a return such that only flat wall joints arerequired between panels.

Flat wall joints between panels may be conveniently formed using acompression gasket on the inner wall of the panel and having anabsorptive clay member disposed between the adjacent panels. Preferablythe adjacent panels have the waterproofing membrane extending around tothe sides of the adjacent panels such that a waterproof engagement isformed between the adjacent panels by the engagement of the respectivewaterproofing membranes with the absorptive clay member. The absorptiveclay member may be held in place by a convenient bead such as a backingrod.

The waterproofing membranes for use in the present invention comprise alayer of absorptive clay disposed between water permeable layers. Theabsorptive clay may be of any convenient formulation, preferably abentonite based material. Bentonite is particularly advantageous as itswells considerably when exposed to water, making it ideal in theformation of a self healing waterproof membrane. It will be appreciatedby those skilled in the art that other absorptive clays may performanalogously to bentonite, if not to the same extent. Bentonite is a claylike mineral consisting largely of montmorillonite and is often derivedfrom volcanic ash.

Whilst a variety of water permeable layers may used to contain theabsorptive clay, it is preferred that a woven geotextile be used assuitable woven geotextiles are both tough and abrasion resistant and canwithstand the abrading forces generally encountered in the formation ofa building structure.

Advantageously we have found that by the use of the building structureof the present invention, the need to over-excavate is substantiallyreduced or eliminated as there is no longer a requirement to access theexternal side of the wall as the panels may be placed in situ with thewaterproofing membrane in place. As such, it is possible to allow forthe maximum utilisation of the building site as there is no need toallow space for the over-excavation of the walls.

As a result of the use of the building structure of the presentinvention a dramatic reduction in the construction program for thebasement work may be achieved. We have found that up to 50% of the workrequired to construct the basement of a building structure may be saved.In addition, the requirement for a variety of trades may be reduced oreliminated. We have found that it is possible to reduce or eliminate theneed for concreters, form workers, steel fixers and waterproofers.

The building structure of the present invention may be produced in amanner which permits the saving of a variety of other services such aswater, electricity, cranage and the like. In addition the need foronsite storage and accommodation may be reduced.

The present invention will not be described with reference to thefollowing non-limiting drawings in which:

FIG. 1 is a cross-sectional side view of a foundation and panelstructure of a building structure according to one embodiment of thepresent invention;

FIG. 2 is a cross-sectional view of a panel joint between adjacentpanels in a building structure as shown in FIG. 1;

FIG. 3 is a cross-sectional view of a foundation and panel of a buildingstructure according to another embodiment of the present invention;

FIG. 4 is a cross-sectional view of a joint between adjacent panelsaccording to the embodiment shown in FIG. 3.

FIG. 1 shows an above ground raft foundation 1 having a footing 1 a. Onthe upper surface of the footing 1 a is channel 2 which extends aroundthe periphery of the raft foundation 1. Precast panel 3 is positioned inan upright position within channel 2.

The foundation 1 is laid upon a waterproof membrane 4 a that extendsbelow the raft foundation 1 and up the edge of the footing 1 a and intochannel 2. The waterproof membrane is terminated at the base of channel2.

Precast panel 3 includes a waterproof membrane 4 b that is attached topanel 3 by a suitable flashing 9. The waterproof membrane 3 extends downinto channel 2 adjacent the waterproof membrane 4 a. Any gap between therespective membranes may be filled with an additional absorptive clay,such as bentonite, filler so as to provide a waterproof engagementbetween the respective waterproof membranes. The waterproof membranesare formed by sandwiching an absorptive clay, such as bentonite, betweentwo layers of geotextile fabric.

The panels 3 are positioned on top of a structural grout 7 so as tomaintain the panels at a desired height above the base of channel 2.Bentonite strips 8 are positioned adjacent the structural grout toprovide improved waterproofing properties.

A spoon drain 8 a is formed on the inside of the panel by a concrete mix8 b.

FIG. 2 shows the joint between adjacent panels 3. Adjacent panels 3 haverespective waterproof membranes 4 on their outer surface and include agroove 12 on their adjacent lateral surfaces. A PVC sheet 15 slidesbetween the respective panels 3 and is engaged by an expanding bentonitestrip 13. The expanding bentonite strip 13 is positioned immediatelyadjacent the PVC sheet and retained in position using a compressiongasket 14 as described in international application no. PCT/AU02/01381.

FIG. 3 shows a building structure according to a second embodiment ofthe present invention. A raft concrete slab foundation 21 is laid upon awaterproofing membrane 22 that extends under the slab foundation, andthe footing 21 b, up the sidewall of the footing 21 b and into channel23. A precast concrete panel 24 is positioned vertically within channel23. The precast concrete panel 24 includes an integral waterproofingmembrane 25 that is formed integrally with the panel 24. The fibres ofthe geotextile material used to form the waterproofing membrane areadvantageously embedded in the concrete of the precast panel 24 toretain the waterproofing membrane 25 in position.

The panel 24 is located on structural grout 26 which is itselfsandwiched between bentonite strips 27. The inside part of the channel23 is filled with a concrete material 28 to form a spoon drain 29 suchthat any water inside the building structure may be drained therefrom.

FIG. 4 shows a wall joint according to the second embodiment of thepresent invention. The wall joint 30 is between respective precastpanels 24. The precast panels 24 have a integral waterproofing membrane25 formed on the outer surface of the panel 24 and extending onto thelateral surface 26 of the panels 24. A backing rod 27 is positionedbetween the respective panels 24 to provide a solid engagementtherebetween. A bentonite strip 28 is disposed adjacent the rod 27 andbetween the respective panels 24 such that the waterproofing membranes25 are in a waterproofing engagement with the bentonite strip 28. Acompression gasket 29 is used to retain the bentonite strip within thejoint 30.

Aspects of the present invention have been described by way of exampleonly and it would be appreciated by those skilled in the art thatmodifications, additions and alterations thereto may be made withoutdeparture from the spirit or scope of the invention.

1. A building structure comprising a footing, wherein the footingincludes a channel, and at least one panel, wherein the panel is locatedwithin said channel, wherein the footing is disposed on a waterproofingmembrane which membrane extends along side walls of the footing and intosaid channel and wherein the panel has an external waterproofingmembrane that is in waterproof engagement with the membrane of thefooting in the channel and wherein the waterproofing membranes comprisean absorptive clay disposed between water permeable layers.
 2. Abuilding structure according to claim 1 wherein the building structureincludes a raft foundation wherein the footing is integral with saidfoundation.
 3. A building structure according to claim 1 wherein thechannel is sufficiently wide such that a spoon drain may be provided onthe inner side of is the at least one panel.
 4. A building structureaccording to claim 1 wherein the panels are precast concrete panels. 5.A building structure according to claim 4 wherein the precast concretepanels include a waterproofing membrane integrally formed on the outerwall of said panel.
 6. A building structure according to claim 1 whereinthe at least one panel is disposed on a structural grout positioned onthe base of the channel.
 7. A building structure according to claim 6wherein an absorptive clay strip is positioned either side of saidstructural grout.
 8. A building structure according to claim 1 whereinthe waterproofing membrane is formed from a layer of bentonite betweenopposed layers of geotextile fabric.
 9. A building structure accordingto claim 1 wherein joints between adjacent panels include a bentonitemember extending between waterproof membrane of the adjacent panels suchthat a waterproofing engagement is provided between said panels.
 10. Abuilding structure according to claim 9 wherein the bentonite member isretained in position between a compression gasket and a structuralelement.
 11. A building structure according to claim 10 wherein thestructural element is selected from a PVC strip or a backing rod.
 12. Amethod of constructing a building structure comprising: (a) layingfooting over a waterproofing membrane; (b) creating a channel in thefooting; (c) extending the waterproofing membrane of the footing intothe channel; (d) placing at least one panel in the channel wherein thepanel has an external waterproofing membrane that is in waterproofengagement with the membrane of the footing in the channel and whereinthe waterproofing membranes comprise an absorptive clay disposed betweenwater permeable layers.